Treatment of antimonial metals



Patented Jan.20, 19 25.

'UNITED STATES mam: r. conoonn, or new Yon'x, N; Y.,

PATENT-"OFFICE.

ass'mNon'To UNITED sTATEs surname,

BEFINING & MINING COMPANY, OF PORTLAND, A. CORPORATION OF MAINE.

No Drawing.

To all wlwm may concern."

Be it known that I, FRANK F. COLCORD,

. a citizen of. the United States, residin at New York cit in the county of New ork and State of ew York, have invented certain new and useful Improvements in the Treatment of Antimonial Metals; and I do hereby declare the following to be a ,full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The invention relates to the treatment of antimonial metals or alloys for the removal of such impurities as arsenic or arsenic and copper. v

I have found that arsenic present in antimonial metals or alloys such as antimonial lead may be conveniently and economically removed without appreciable effect upon the antimony by treating the molten alloy with caustic alkali, such as caustic soda, or an alkali salt, such as soda ash, at suitable tem peratures above those at which the salts or caustic melt. V

The invention is of particular value as applied to the nurig ing of antimonial lead alloys whether pro uced by themixin of metals or as a product in metallurgica refining operations and will be further ex plained in connection-with the puri ing of antimonial lead alloy such as usual y produced in the refining of. lead bullion. Such alloys usually contain small percentages of arsenic and copper say from to 1%% arsenic and from to co per. While for some uses the resence of t ties is not particu arly detrimental, it renders the alloys unfit for other fieldsof use. In treating these alloys the preferred mode of operation is as follows: The moltena1 loy lsbrought to a temperature between 900 and 1000 F. andthe caustic soda is added in about the proportion of three pounds of caustic' to each pound of arsenic in the alloy. The total amount of caustic .is best added in successive fractional addi tions, the number of such additions depending upon the amount of arsenic present and the degree towhlch it is to be removed. The

caustic soda is thoroughly stirred into the igitation of the molten metal continues unthe caustic is spent, which usually ocese impuri- TREATMENT or "anrmoman nn'rans. 1

' Application filed November 22, 1928. Serial No. 676,854.

curs in about an hour. The skim thus formed is removed and then the treatment with caustic soda is repeated until by test the removal of, the arsenic to the desired degreeis shown. During the successive treatments -with caustic soda the temperature of-the molten metal is preferably maintained within an approximate range of from 900 to 1000 F. although somewhat logger and higher temperatures are permissi e.

" I have found that with the above 'methodl the arsenic may be economically and, efficientl removed entirely or to any desired egree from antimonial lead alloys without materially affecting the antimony which is usually present in amounts from 4 to 20%. ,This method is also applicable to the purifying of antimony-tin-lead alloys as the caustic soda treatment, will remove the arsenic from the molten ailoy without affecting either the antimony or tin contained in an .antimonial lead alloy of this character. It is also applicable to the purifying of such other antimonial 'metals or alloys as are of a character to admit of similar treatment at temperatures which will result in the removal of the arsenic without materialefiect on the antimony therein. f

Similar results may be secured bglike treatment with alkali salts such as so a ash although the range of temperature at which the treatment. should be effected in order to secure the best results is somewhat higher than with caustic soda.

In case the alloy to be purified also contains copper as an puritfy;e this may be removed either before or a 1, preferably before removal of the arsenic by treating the molten alloy with sulphur at a comparatively low temperature. The amount of sulphur'to be added will vary with the amount of copper present and'will be approximately one pound of-sulpliur to each pound of copperr- The sulphur preferably,

but not necessarily, in the form of flowers of sulphur, is thoroughly stirred into the molten alloy while the temperature is preferably maintained somewhat below the burn ng point of sulphur or at an approximate range of from 560 to 600 F. The copper Wlll quickly unite with the sulphur and will float on the molten alloy in the form of dross. After the stirring has continued say for about half an hour, it is stopped and the temperature of the molten metal lowered to about 550 F. and the dross containing the copper is then removed.

By the method described arsenic or ar senic and copper may be' quickly and economically removed from antimonial lead alloys and other metals or alloys containing antimony which are of a character to admit oftreatment by this method and these altion.

What isclaimed is: 1. The method of purifying autimonial lead alloys which consists in subjecting the molten alloy to the action'of an alkali at Y temperatures to cause the arsenic in the alloy to unite with the alkali without affecting the antimony.

2. The method of purifying antimonial lead alloys which consists'in treating the' molten alloy with caustic soda at a temperature above that at which the caustic soda melts to remove the arsenic which is in the alloy without affecting the antimony.

3. The method of purifying antimonial lead alloys which consists in treating the molten alloy with caustic soda at an approximate temperature range of from 900 to 1000 F. to remove the arsenic which is in the alloy.

4. The method of purifying antimonial lead alloys which consists in treating the molten alloy with sulphur to remove the copper therefrom and with an alkali to remove the arsenic without affecting the antimony.

.5. The method of purifying antimonial lead alloys which consists in treating the molten alloy with caustic soda at an approximate temperature range of from 900 to 1000 F. to remove thearsenic and with sulphur at an approximate temperature range of from 550 to 600 F. toremove the copper. 1

6. The method of purifying antimonial.

' lead alloys which consists in subjecting the -molten alloy to agitation and simultaneous ly to the action of an alkali at tempera-' tures to cause the arsenic in the alloy to unite with the alkali without affecting the antimony.

7. The method of purifying antimonial lead'all oys which consists in agitating the molten alloy and simultaneously treating it with caustic soda at an approximate temperature range of from'900 to 1000 F. to

remove the arsenic which is in the alloy.

-8. The method of purifying antimonial metals which consists in subjecting the molten metal to the action of an alkali at temperatures to cause the arsenic in the metal to unite with the alkali without affecting the antimony.

9. The method of purifyin antimonial metals which consists in su jecting the molten metal. to agitation and simultaneously to the action of an alkali at tempera-tures to cause the arsenic in the metal to unite with the alkali without affecting the antimony.

10.- The method of purifying antimonial metals which consists in treating the molten metal with caustic soda at an approximate temperature range of from 900? to 1000 urifying antimonial F. to remove the arsenic which is in the metals which consists in subjecting the molten metal to repeated treatments with caustic soda at an approximate temperature range of from 900 to 1000 F. to effect fractional removal of the arsenic which is in the metal.

14. The-method of purifying antimonial metals which consists in intermingling caustic soda with the molten metal at an approximate temperature range of from 900 to 1000 F. to remove a part of the arsenic which is in the metal and repeating the treatment until the desired reduction in the arsenic is effected.

15. The method of purifyin antimonial metals which consists in -su jecting the molten metal to the action of a caustic alkali at temperatures to cause the arsenic in the metal to unite with the alkali without affecting the antimony, and agitating the mixture'during the treatment by blowing air'therein. 

